1. Field of the Invention
The invention relates to a method and a device for operating a manure transport device for livestock breeding operations.
2. Discussion of Background Information
Manure transport devices for livestock breeding operations comprising a manure conveyor belt driven in a circulating manner arranged underneath a stall floor and having a return roller are known, for example, from German Pat. No. DE 195 14 574 C1. This known device is suitable for poultry breeding operations where poultry excrete a relatively solid but moist manure in which a separation of manure and urine is not possible.
However, with the device according to DE 195 14 574 C1, the problem arises that it is difficult to guide planar textile structures as conveyor belts because they always have the tendency to slip from the drive and return rollers due to the fact that the textile structure does not allow a trouble-free guiding of the belt. Accordingly, with this known device, the straight course of the belt has been ensured by driving the return roller always at a higher rotational speed than the drive roller. Experiments have shown that this arrangement makes a trouble-free guiding of the manure conveyor belt possible.
Alternatively, U.S. Pat. No. 3,119,373 describes a demanuring cleansing arrangement in which an inclined plane preferably covered by plastic sheets is formed beneath a grating forming the stall of the stable animals. A pusher can glide on and can be moved over the inclined plane by a motor with the aid of a chain and roller drive. In order to maintain the conveyor device for this dung pusher constantly under tension, a tensioning device in the form of a spring is arranged at one of the two rotating shafts. The spring acts on the bearing of the rotating shaft for the roller that is not driven. Although the return roller is supported in a floating manner, this is not a driven return roller.
With livestock breeding operations in which animals are kept that excrete solid manure and liquid urine (e.g., pigs), considerable difficulties arise in carrying away this very moist, mushy mixture. A manure removal arrangement for small-animal farms is known, for example, from Published German Patent Application No. DE 35 28 604 A1. The arrangement has a two-part design comprising a liquid-tight floor part which serves as a urine collection channel, and a fall-through grating arranged above this liquid-tight floor channel. This fall-through grating is formed by a conveyor assembly or conveyor belt that does not comprise a circulating upper and lower belt half, but, rather, is composed of a single layer of a moisture-permeable material. The layer can, for example, be a mesh-like textile.
The use of such an arrangement in the case of swine breeding operations would not be successful, since the solid manure involved is still relatively soft and would fall through the fall-through grating.
If conveyor belts are used in swine breeding operations for the removal of the manure, a very quick fouling of the return rollers occurs so that the conveyor belts slip off laterally. Likewise, attempts in practice to embody the drive roller and/or the return roller in a convex manner in order to achieve a straight course of the conveyor belt have not been successful because the fouling is too great and the solid manure components equalize the convexity of the return roller and drive roller.
Moreover, attempts to design the return roller and/or drive roller as latticed rollers in order to achieve an appropriate guidance have not been successful either, since these rollers become clogged inside the lattice extremely quickly.
A method is known from US Patent Application Publication No. 2005/0028748 A1 in which the return roller can be shifted in the longitudinal axis of the manure conveyor belt. The return roller is acted upon by an adjustment device through which a tensioning of the manure conveyor belt is regulated, the adjustment device producing the tension on the manure conveyor belt being intermittently active. The return roller may be driven in the direction opposite to that of the drive roller. This known device has proven itself in practice, but is very expensive in constructional terms.